Correlation functions in the prethermalized regime after a quantum quench of a spin chain

Abstract

Results are presented for a two-point correlation function of a spin chain after a quantum quench for an intermediate time regime where inelastic effects are weak. A Callan-Symanzik-like equation for the correlation function is explicitly constructed which is used to show the appearance of three distinct scaling regimes. One is for spatial separations within a light cone, the second is for spatial separations on the light cone, and the third is for spatial separations outside the light cone. In these three regimes, the correlation function is found to decay with power laws with nonequilibrium exponents that differ from those in equilibrium, as well as from those obtained from quenches in a quadratic Luttinger liquid theory. A detailed discussion is presented on how the existence of scaling depends on the properties of the initial state before the quench.